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ESX/ESXi 4.x
# esxcli nmp device list -d naa.50002ac0005800ac
NOTE: If I/O is active to a LUN and an attempt is made to modify the path policy, a failure can
occur:
error during the configuration of the host: sysinfoException;
Status=Busy: Message=Unable to Set
If this problem occurs during an attempt to change the path policy, reduce the I/Os to that LUN
and then try making the desired changes.
Performance Considerations for Multiple Host Configurations
The information in this section should be considered when using multiple ESX hosts, (or other hosts
in conjunction with ESX hosts), that are connected in a fan-in configuration to a pair of HP 3PAR
StoreServ Storage ports.
NOTE: For ESX 4.0 systems, HP recommends changing the ESX Scsi.ConflictRetries from its
default value of 80 to a value of 200 when connected to an HP 3PAR StoreServ Storage running
HP 3PAR OS version 2.2.4 or earlier. This change lengthens the time allowed for I/O retries due
to ESX SCSI-2 reservation conflicts on VMFS LUNs caused by delayed processing of SCSI-2
reservation commands on the HP 3PAR StoreServ Storage, thereby helping to avoid VM I/O failure.
You can change this value using the VMware ESX VI/vSphere client: In the ESX host, select the
Configuration tab, select Advanced Settings for software, select Scsi, scroll to Scsi.ConflictRetries,
and change the value in the field. Click OK to complete the change. A reboot is not required for
the change to take effect.
This does not have to be done for ESX 4.1 or ESXi 5.x systems.
ESX/ESXi Handling SCSI Queue Full and Busy Messages from the HP 3PAR StoreServ
Storage Array
VMware ESX Releases through ESX 3.5 Update 3
The default behavior of an ESX 3.5 update 3 and older servers to Queue Full and Busy SCSI
messages from the HP 3PAR StoreServ Storage is to treat them as valid commands and to continue
sending data. When continued outstanding commands are being sent to an HP 3PAR StoreServ
Storage port, the port cannot recover and stops responding for attached hosts.
This type of action is critical where QLogic HBAs are used on the HP 3PAR StoreServ Storage
because, when the storage port stops responding, the QLogic driver on the HP 3PAR StoreServ
Storage has to issue a reset of the affected port.
The time in which the HP 3PAR StoreServ Storage port is at full capacity and the reset time of the
port does not trigger a failover in the ESX host, since the ESX host never detects the port going
away. This results in a virtual machine crash. There are two solutions:
• Upgrade to ESX 3.5 Update 4 or later.
• Control the IO that each array port receives by manipulating the HBA queue depth (see
“Modifying the Tuneable Parameters for Queue Depth Throttling in ESX 3.x” (page 49)).
Performance Considerations for Multiple Host Configurations 47